Clam-shell excavator.



A. ElLERSGA/mn.

CLAN! SHELL EXCAVATOR.

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CLANI SHELL EXCAVATOR. APPLICATION FILED Dc.23,1915.

Patented June lh 1918.

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wwf?" A. ElLERSGAARD. CLAM SHELL EXCAV/WOR. APv'ucATloN FILED DEc.23.1915.

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- in the specification.

lclam shell buckets,

ASBHEB. EIIJBBfSrGl-AABD, 'OF' CHICAGO, ILLINOIS, ASSIGNOB; TO LINILBBLT COMP CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS. v

etant-stanti. nxcavnron.

.IBBOBO Specitcation of Letters Patent.-

Fatented dune I, MIIB..

Application filed December 23, 1915. Serial No. 68,320.

c1tizen,) residing at Chicago, in the county' of Cook and State of Illinois, have invented a certain new and useful Improvement in Clam-Shell Bxcavatoraof which the following is a specification. I

y invention relates to improvements 1n and has for one object to provide bucket closing means which will give great closing power lwithout a disproportionate resistance to opening. Another object is to provide a chain bucket which will have an increased closing power wherein the closing force will not decrease unduly as the bucket approaches the closed condition. Another object is to provide a did'erential chain closing mechanism for a clam shell bucket. her object is to .provide means for drawing in a part of the closing chain means for paying out another part to compensate for the change in the radius armthrough which the closing force is applied. Other objects will appear showing the Fig 5 is a section A.along the line 5 5 of Fig. d; 1 l

6 is a section along the line 6-'6 of 1g.

Figs. 7, 8, 9 and l0 show diagrammatically the position of the closing chains and closing cams and associate parts' at the open position. at twol partially closed positions, and at the fully closed position.

Fig. il is a detail end` elevation of a slightly modiiied torni l.showing some of the ttf parts in the closed position `with the closm` chains removed.

12 is .an end elevation` ot modied form of scraper bucket with my device ap` plied theret s. 6

Fig. 13 is a slde elevationot Fig. 12;= Fig. Mis a side elevation et the modied y invention is illustrated more or less diagrammatically in the trolling `form showing the buckets in the open posi- .tion. y

Fig. 15 is a section along the line 15-15 ot Fig. IA.

Like parts are indicated byv like letters in all the figuresl rReferring first to the preferred form shown in Figs. ly to 11, A, A1, jaws. rllhey have upwardly projecting from them the arms A2, A3, pivotally tied together by the pin At. A, A6 are built up shear legs pivoted respectively on nthe outer upper edges of the buckets A, A1 and pivoted together on the yoke A".

l 1s a drum rotatably mounted on the pin A4. About this drum is wound a cable B1, which cablev passes up over the sheave B2 on the yoke A7 to a suitable source ot power. BS is a hub integral with the leg A2 and rotatably mounted on the pin At. On this hub is keyed a segment Bt. B5 is a cam integral with the drum B and mounted to rotate with it upon the pin At. a cover of guard about the lower portion of the drum B. It is mounted on and integral with the segment Bt.

C is a hub rotatably mounted on'the arms C1 downwardly projecting from the 7 C2 is a cam on one side of the hub immediately above the segmentk Bt. C3 is a cam on" the other side of the hub ediately above the cam B". Ct is al cam conchain. It is anchored atwone end on the lower extremity of the segmentBt and at the other end on the outer extremit ot the cam C2. C is the closing chain. 1% is anchored at its lower extremity at the innermost point of the cam B, and at its upper extremity on the outermost pgint of the cam C3. 'lhe arrangement oit' cams and chains is such that when in the open position the cam controlling chain is wound almost entirelyod' the segment cam C2, and the closing chain is anchored on but wound od the cam'A B5 butwound clear around the cam C, tially a full revolution of that cam will be required to pay ed the closing chain. i In the modied tor-'1n shown in Figs. l2 to 15,*the bucket members D, B1, are providedwith long upwardly extending B2, lDS, pivoted on a I-shaped yoke, Bt the central arm of the I', extendmg downwardly B6 is f to a point approximately intermediate the yoke" are bucket and Ior the MMI ion

tl'mS IIA Ds'is a hoisting line attached to a yoke D, The yoke carrles sheaves D7, D7, and supports the chains DB, D, which chains are pivoted at their lower upper ends on horns D1, D, on the arms D2, D.

E is a closing drum. E1 is a closing cable wound about it, which cable leads up between the sheaves D" to a suitable power source. It will be noted that instead of having as in the preferred form one closing and one controlling chain, I provide two. This is necessitated by the fact that in this modified form it is necessary to draw each of the bucket 'or scraping members in toward the center, whereas in the previous form it was only necessary to draw the central pivot connection between the two buckets, upwardly toward the apex of the shear frame. Aside from this difference the operation is exactly the same. Certain changes in det-ail, however, are necessitated. The cam arrangement on each of the arms D2, D, is exactly the same as the cam arrangement onthe yoke C1. The winding drum,however, has integral therewith on either side thereof the spools E2.l Upon these spools are adapted to be wound the closing chains. The controlling chains are provided with stirrup or link connections E4', which are pivoted on the pin Eli tying the parts together.

" It will be evident that. while I have shown 1n my drawlngs. an operative device, still many changes might be made in size, shape and arrangement of JIparts without departingv from the spirit o my invention.

he use and operation of my invention are as follows:

Referring first to the preferred form with the parts 1n the position shown in Fig. 3, it w1ll be understood that the arrangement of the chalns and cams is that shown in Fig.

y 7 the upper cams being integral and rotatably mounted on their pivoted pin, are free to turn. The operator commences to draw 1n on'the hoisting cable. This cable at the start 1s wound three times about the hoistlng drum. It will be noted that the point at which the controlling chain is attached to the cam on the drum is about twenty degrees below the horizontal. One revolution of the hoistingdrum will draw in the hoistlng cable one revolution, and this will pull the upper vcam about which the chain is wound over through yapproximately ninety degrees as indicated. The controlling chain will at that time commence to be wound up on its upper cam. The closing movement of ]aws having commenced the segment upon which the lower end of the controlling chain' is anchored, will travel down through ap- A proxmately thirty degrees. The next complete rotation of the -`hoist-ing drum will wind the hoisting chain once more about it.

y The chain is .a flat one, and as the movement continues, will wind about itself on the' drum or cam. The lever arm is thus increased and the closin force exerted dccreased, but by this time the upper cam about which the closing chain is wound, will Y have rotated to decrease that lever arm, and

-upper cam about which the closing chain is wound, will not payout that chain quite as rapidly as would be the case if the rotation of the cam 'were controlled by the approach of the two axes of rotation. The next revolution pays out all the cable on the drum, Winds up all the closing cable and leaves the parts in the position shown in Figs. 10, 1 and 2. The chain by that time will have been completely paid out from the upper cam and the controlling chain will have been drawn down about the lower shaft to the full length of the segment and up about the upper shaft upon the cam. Thus it will be observed that the cam arrangement, as shown causes t-he increase in lever arm through which the closing force works on the drum shaft to be counterbalanced by a decrease in the lever arm through which the controlling chain works, and an increase ofI the lever arm through which the closing chain works on the upper shaft, thus the turning moment available as a result of the tension in the cable is at all times the same independent of the number of coils of chain about the windlass or housing drum shaft.

The operation is exactly the same in the case. of the modified form, the only difference being that there are two sets of closing and controllin chains at work, each set tending to pul its own bucket toward the center line.

Thus the arrangement is to a large extent productive of a differential result. That is to say, while one -chain is paid out another one is drawn in. The movement of one chain being greater than the other results in a gradual drawing together of the chain anehorages which gradual drawing together'is not as rapid as the movement of the chain.

In a certain sense the two chains, that is to say, the chain which I have called the closing chain, and the chain which I have called the cam controlling-chain, may be regarded as two parts of the same loop of conmovement, and this differential chain movehill titl

' shaft A4 to move upwardly. The tension in dll :so arranged that ment the consummation of vthe torce is available ipeaaoa be obtained by some ment might obviously the double cam arother mechanism than rangement. 'ff

The mechanical movement which operates to close the b ckets does so by drawing together two ivot axes. That is to say, the pivot axes a ong which the two buckets are articulated is drawn upwardly toward the pivot axis are articulated. This upward movement of the bucket pivoted axis-is caused by three\ separate coperating torces,fone of them the upward .tension in the closing cable. tension is always the same from the beginning to the end of the closing movement. This tension or force acts through a xed lever arm tending to rotate the power drum. llt is this 'rotation ot the power drum which operates the othertwo cables which ll have for convenience termed the cam controlling epd the closing cable, though obviously both o th em are closing cables in a sense. These two cables and during the very true their 'cams are closing movei'orce exerted them is constant, but the force each individual cable obviously it is the varying iorce exerted when compensated ilor` by both of exerted by varies', and

exerts a constant force at all times from the commencement to the end of the closing movement. This can best be seen in llligs. 7 to 10 which are applicable to both modihcations. That is to say, the only change to make them applicable to the second type would be to duplicate the system.

We will therefore consider the one modiiication. ln the positionshown in lFig. 7 when the shall-th4 is rotated the chain C5 tends to wind .about the hub B5 and the rotation of the hub exerts a certain predetermined tension in the 'chain tending to cause the the chain is resisted chain Ct which tends the cam Caby sembly, but

by a tension in the to prevent rotation oit" the weight ot' the bucket assince the rotation ot the hub shortens the chainftll, -the shalt d must perforcc rise. .This permits the chain Ct to pay out and allows a rotation ot the cams- Cz, C, so that at the end oi*l the hrst revolution of the power drum the cam C will have rotated until the chain Ct is 'wound 'up upon it t'or` a short distance. This permits a rotation of the cam C3 until the chain C has wound oilE it slightly. through which the chain 9C acts on the cam 3 is increased. The lever arm through which the hub acts on the chain C5 is also increased owing to one coil of chain being wound upon another. The torce tending to rotate the hub is constant, so that a smaller tending to pull. the chain but this smaller tor ia The lever arm C downwardly,

equalized by the longer lever arm through which that chain works, tending to rotate the cam C3 so that `the tension in the chain Ct is now increased. This process continues as sho in Fi s. 9 and l0 with the tension in the chain 5 decreasin proportionately at each revolution oli t e power drum and the tension in the chain Ct increasing proportionately at each revolution ot the power drum until the parts have been ydrawn into the position shown *in lFig. l0.

l have spoken ,above of the did'erent lever arms available.` llt is understood, ot course, that the reason why there is a ditierence in leverage is because ot the tact that the chain as 1t due to the rotation of the hoisting drum piles coil upon coil and increases the lever arm, thus decreasing the advantage ot the mechanism. This increase in lever arm is compensated for as above pointed out by the cooperation ot the two opposed cams. These cams are arranged so that while these wind up, in this case 83 inches of chain the travel between the head and the drum is only 54 inches. The three toot travel ot chain beyond the travel of the mechanism itself is taken care of by winding ythe chain od one cam and winding it on another cam and it is this cooperation ot these two cams and the chain sections wound about them which produces the desired result whereby 83 the drum with respect to the comprising two other, a power `cham and means responsive to the relative angular movement ot the two jaws and to the rotation ot the power drum for compensating for thev change in the length ot the lever arm throng which the chain acts, resulting from the winding ot one coil ot chain upon another on the hub as the cable is wound o the drum.

2. dn excavating bucket comprisingtwo jaws pivoted one on the other, a power drum, a cable wound a plurality ot times about it., a hub integral therewith, and a closing chain having on'e end anchored thereon, a head supported above the jaws, a pair ot oppositely disposed cams rotatably mounted on the head ing anchored to and adapted to wind about one ot the cams, a controlling chain anis wound about the hub' the closing chain be' hill i inches of chain travel gives 5d inches ot 'y lllllh chored on and adapted to wind about the i lldtl ,and the like comprising jaws pivoted one`on the other, 'a power drum, a' cable wound a plurahty of tlmes about it, a hub integral therewith, and a closing chain having one end anchored thereon, a head supported above the jaws, a pair of oppositely disposed cams rotatably mounted on the head the closing cham being anchored to and adapted to wind about one of the cams, a controlling chain an chored on and adapted to wind about the other cam, said controlling cham being anchored at its free end on one of the jaws, a segment on the jaw about which said controlling chain is adapted to be wound.

4. Closing means for clam shell excavators a power drum and means for rotating it, a the drum, a two part closing cham having one end adapted to be wound about the hub, another end of the chain being' anchored on the bucket, two cams removed from the power drum oppositely disposed and adapted -to rotate in unison, the two remaining ends of said two part chain being anchored respectively one upon each of sald cams.

5. Closing means for .clam shell excavators and the like comprising a power drum and means for rotating it, a hub integral with the drum, a two part closing chain having one end adapted to be wound about the hub, another end of the chain' being anchored on the bucket, two cams removed from the power drum oppositely disposed .and adapted to rotate'in unison, the two remaining ends of said two part chain being anchored respectively upon one of said cams, the relative arrangement off' cams and chains being such that as one chain is wound about one cam the other chain is wound off the other cam. l Y

6. A clam shell bucket comprising two pivoted bucket members, a closing drum mounted for rotational on their pivot axis,

a chain drum mounted orrotation with the closing drum, a controlling segment mounted for `rotation concentric with the closing drum upon one offsaid bucket members,

shear legs pivoted on the bucket members and pivoted together above the bucket member pivot axisgwa pairof cams mounted for rotation upon the shear leg pivot axis, said cams being oppositely disposed, a closing chain anchored on uthe cham drum and on one of said cams, a controlling chain anchored on the controlling segment and the j other cam, a cable wound about the closing drum, the relative positions of the parts being such that when the cable is wound about the closing drum the closing chain is wound about its cam and anchoredon but not wound about the chain drum, and the con- ,trolling chain is anchored onbut not woundl about the controlling segment and the controlling cam.

7. A mechanical movement comprising a hub integral with rotating at one end and upon said chain drum and controlling segment respectively at the other, the relative position of the parts being such that when one chain is wound about the chain drum it is wound off its cam and the other chain .is wound upon its cam and also upon the segment. y

8. An excavating bucket comprising two jaws pivoted one on the other, a head supported above them, a closing chain and a controlling chain interposed between the support and the jaws, cams oppositely disposed adjacent one end of each of said chains, the chains'being anchored on the cams the opposed ends of the chains being attached one of them to a winding drum rotatably mounted the other to a segment rigid with one of the jaws, a power drum and means for rotating it to rotate the winding drum to wind the chain thereabout, the relative position of ,segment, winding drum and cams being such -`that as the rotatlon of the winding drum ahead located above their pivoting point connecting arms joining the head and the jaws themselves and a hoisting drum mounted for rotation about the pivoting point of the driving arms and means for rotating it, a hub mounted for rotation with the hoisting drum, a cable adapted to be wound about such hub such cable consisting of a closing chain, a compensating device mounted on the head upon which said closing chain is anchored and a controlling chain anchored at one end on the compensating device and at the other end mounted on one of the drivin arms, means responsive to the rotation fof such "driving arm as 'the bucket is closed foridrawing in on the controlling cable.

10. Closing means for a clam shell bucket comprising a closing drum and means for it, a compensatin device removed from t e closing drumfa ub mounted for rotation with the drum, -a closing cable anchored at one end upon such hub and adapted to be wound about it and at the other end on the compensating device, a controlling cable mounted at one end on the compensating device, at the other end on a mem ber adapted to rotate with the bucket as it is closed.

l 11. Closing means for a clam shell bucket comprising a closing drum and means for mennen rotating it, e compensating device removed es it is closed seid compenseting device compp from the closing drum, a hub mounted for pmsinge peine ot opposed cams.

rotation with the drum, :t closing cable y Signed et @bien o, in tbe county of @ook anchored et one end upon such hub and end @tete et minols this 20th dey of Decem- 5 adapted to be Wound about it and et the ben, 1915.

other end on the compensating device, e, con- ASGER ELERSGAARD.

trolling cable mounted et one end on the Witnesses:

compensating device, et tbe otherI end one Mmmm M. Lnvnmmn,

member edeptedto rotete with the bucket @summe Deens.. 

